This section provides background information related to the present disclosure which is not necessarily prior art.
IDLE mode is a work mode for a mobile station with regard to the mobile broadband wireless access system defined by IEEE 802.16e. In IDLE mode, a mobile station (MS) may move in a wide area, receiving downlink broadcasting service information at regular intervals. A base station (BS) informs the MS of the delivery of the downstream service by broadcasting a message. The MS, when roaming within this area, does not have to register with the BS at the cell where the MS roams. In addition, the MS does not have to perform normal operations such as handoff when roaming into a different cell. Advantageously, the MS power and the resources of air interfaces may be saved.
A plurality of BS may constitute a group, called a Paging Group (PG). The goal of the paging group is to form a continuous area in which the MS does not need to send upstream service but may decide, through downstream paging channel, whether there is any downstream service sent to the MS. The paging group must be large enough to ensure that most mobile stations are retained in the same paging group within a relatively long time period. Moreover, the paging group must be small enough to ensure a reasonable overhead for paging MS in a paging group.
During normal operations with a certain serving BS, the MS may send a message requesting for entering the IDLE mode. Similarly, the Serving BS may also send a message, actively requiring the MS to enter the IDLE mode. No matter it is the MS that actively requests to enter the IDLE mode, or it is the Serving BS that actively requires the MS to enter the IDLE mode, MS has to complete registration and enter the IDLE mode in a prescribed time period.
The current World Interoperability for Microwave Access (WiMAX) under enactment defines a paging reference model in IDLE mode. In the paging reference model illustrated in FIG. 1, the Access Service Network Gateway (ASN_GW) does not take other physical net elements and logic entities in the WiMAX network which are irrelevant to paging procedure into consideration. The WiMAX paging reference model is illustrated in FIG. 1 in the subsequent detailed description.
According to the paging reference model in FIG. 1, when MS actively send request to BS1 (Serving BS) for entering the IDLE mode, or the BS1 instructs the MS to enter the IDLE mode, the exchange of information between MS and BS1, between BS1 and the back end net element, ASN_GW, may help to inform a paging controller (also known as an anchor paging controller, implemented in the ASN GW1) that the MS has entered the IDLE mode and the paging controller may save the status information, paging information as well as service flow information of the MS in a corresponding location register (LR). The MS may carry information which the MS requests to preserve when it is entering the IDLE mode in the IDLE request message sent to the BS1. The BS1 may also configure similar information in a response to the IDLE request message so as to inform the MS of the related information preserved in the LR and inform the MS of the paging controller ID. Moreover, after the MS enters the IDLE mode, R4, R6 interfaces need to be released whereas the R3 interface between the home agent (HA) and foreign agent (FA) needs to be preserved.
Scenarios that the MS updates its location are described below.
(1) Paging Group update, referring to location update in that the paging group changes. When the current paging group broadcast by the BS, received by the MS, is inconsistent with the paging group which was assigned to the MS, location update needs to be performed and new paging group as well as new paging parameters need to be assigned.
(2) Timer update, referring to location update in that the timer times out. After the MS enters the IDLE mode, both the network side and the MS will initiate a timer for IDLE mode management. The MS will perform location update before the timer times out.
(3) Power off update, referring to location update when the MS powers off in IDLE mode. In IDLE mode, if the MS powers off, location update may also need to be performed with the network side. In the prior art, the location update in the case of power off is just a normal location update, which does not delete the MS context preserved in the network entity.
(4) MAC Hash Skip Threshold update: location update caused by exceeding MAC Hash Skip Threshold.
The prior art simply describes the location update procedure in normal situations, or the location update procedure in the instance where the paging group changes. However, the prior art fails to consider the location update procedure in exceptional cases (e.g., network logout as a result of power off and congestion of the network, etc.). One approach to addressing this problem and one way to handle the location update procedure in the exceptional cases differs from location update procedure in the instance where the paging group changes according to the prior art.